This could be my last Christmas

It's not often that you can walk into work proudly boasting that they have just helped to save someone's life. But that is the opportunity we are giving you today.

A day off work and a short stay in hospital could be all it takes to ensure that this Christmas isn't Penny Phillips's final one.

When she cuddles her grandsons Nathan, three, and four-month-old Noah, Penny's feelings are rather more intense than the usual rush of grandmotherly love. Penny looks healthy enough, but she is dying of leukaemia. Unless a suitable bonemarrow donor can be found, she is unlikely to live for more than a few months.

A few days ago, her regular bloodtest revealed that her "blood counts", which have remained stable for six months, have fallen worryingly, which means, simply, that her condition is beginning to deteriorate.

"The most horrible thing of all," she says quietly, "is the thought of not seeing my grandchildren grow up."

For Penny and her family - her husband Michael, their sons Tim, Ben and Jon and their families - the past 16 months have been traumatic. A "frenetically busy" drama teacher who lives on a houseboat near Heathrow, Penny had felt exhausted at the end of the summer term in July 2002 - but then, that wasn't uncommon. Suspecting anaemia, she had a blood test, and was diagnosed with leukaemia.

"It was a terrible shock," says Penny. "I'm 58, and could be considered 'past it' but not in my husband's eyes. When they told us that I would die within a few months unless I had chemotherapy, I turned to him and said, 'I'm sorry, this is the end.'

He grinned at me through his tears and said, 'No, this is just the beginning.' And he was so right."

Penny Phillips and Michael, 62, her husband of 38 years, are still, clearly, hugely in love and upbeat, despite what they have been through in the past 16 months. They are the sort of couple who puncture each other's conversation with pithy asides, and who link fingers without noticing that they are doing it while they discuss the day's schedule.

They closed the drama school at once, and Penny endured four gruelling five-week bouts of chemotherapy and isolation in hospital. "We went to hell and back through the treatment, though the team at Hillingdon Hospital were excellent," says Penny, a tall, imposing figure who manages to talk in a matteroffact, cheerful way about her plight. "They sent me home as often as they could, but each time I went back in, I was less of a person than I was before. By the end I had black teeth and no hair at all. I couldn't eat or drink, I couldn't talk, I couldn't concentrate - it's the most grim experience imaginable."

When the leukaemia proved to be a type which fails to respond to treatment, the future, such as it was, looked even bleaker. A transplant of stem-cells, taken from bone marrow, is now Penny's only chance of beating the disease.

She was transferred to King's College Hospital in south London, which instigated a search for a bone-marrow donor through the Anthony Nolan trust, but two sweeps of the country have failed to find a suitable donor, and, as Penny knows, time is running out.

"The awful thing is that there is so little I can do," she says. "For some cancers, you can eat certain foods, or try alternative cures, and there will be a percentage of people who survive. But people never survive myeloid displasia without a bone-marrow transplant. I was brought up not to think of the concept of 'never'. But without a transplant, there is no hope.

"One of the few things I can do is appeal for people to volunteer as bonemarrow donors. Everyone knows that you can be an organ donor after your death, but very few people seem to know that you can donate bone-marrow while you're alive and save someone's life. It's not difficult.

"If you are in good health and between 18 and 40, all you have to do is register with the Anthony Nolan Trust and have a blood test. If a recipient is found who matches your tissue type, you will need to spend two days in a private hospital where stem cells are harvested through the pelvic bone under general anaesthetic. You then need to take a week off, and the Trust will reimburse your loss of earnings for that time."

She is not looking for sympathy - her conversation is peppered with bursts of laughter, rather than sad silences - so much as action. While the next donor-search is conducted, Penny is living quietly at home, on the snug, homely houseboat to which she and Michael retreated when Michael's stationery business folded five years ago and they had to sell their four-bedroom house. Even on a dank winter morning, it has a happy, warm atmosphere. Flowers brighten the sideboard, and photographs of their sons in graduation robes adorn the walls. All three boys abandoned other careers to work for the Church - Tim, 31, and Ben, 28, are curates in Leicester and Cockermouth, while Jon, 24, is a youth group leader in Chester.

Living with such a death sentence, most people would be forgiven for sinking into relentless depression, or being filled with anger, but that, Penny feels, would be pointless. She, on the other hand, insists that the past year has been the best of her life. "Not working, living on a boat, through the best summer we've ever had, seeing all your best friends, and being able to linger with them, two new grand-babies. And being loved. It's an incredible feeling. I should have realised I had all this before.

"The ridiculous thing is that I've always been a glass-half-empty sort of person, a worrier of huge proportions. I always felt negative and anxious. But now that I'm dying, I'm really living. That's the terrible joy of this year. I've never been so happy. But short of a miracle, I won't be around this time next year."

She's still not used to seeing a fat, grey-haired woman looking back at her from recent photographs; until the chemotherapy, her hair was red, and she weighed 12 stone. But during the treatment, she lost nearly three stone, and the ordeal of trying to force down food to rebuild her strength, through a throat that couldn't swallow - chemo destroys the mucous membranes that line the mouth and throat - was so hideous that she has been overeating since then; a pre-emptive measure against future chemotherapy. "I'd rather be fat than go through that again," she says flatly.

I had gone to interview Penny equipped with waterproof mascara and a fistful of tissues. But she's so lively and frank about the hideous reality of her illness, so funny and friendly and full of life, that I didn't need them.

Back at home, as I transcribed the tape of the interview, my husband looked up from his desk. "Is that the woman with leukaemia?" he asked, puzzled. "I thought she was dying. All I can hear is gales of laughter." At which point I did burst into tears.

Penny Phillips is a remarkably brave woman, but she is dying, and she doesn't stand a chance unless people volunteer to donate bone marrow, to give her and others in her position the possibility of more years with their loved ones.

The hospital will do another sweep of the country for a bone-marrow donor in a month or two. "If more people have volunteered by then, who knows?" says Penny. "One of them might be a match." And just for a moment, she dares herself to think forwards. "If it all works out - then I could live a normal span of life. I'd be so good at that, at living. I'd really quite like to have a chance."